Lag-indicator.



W. H..'FREEDMAN. v

LG INDIT.; W ik v APPLIOATIN FILED JUNE 13, 190s. nnnwlzn nu 9, 190e.

903,966. Patented Nov. 17,1908,

fur Non!!! rms: t0., Hummm, n. c.

WILLIAM H. FREEDMAN, OF BURLINGTON, VERMONT.

LAG-INDICATOR.

Specification of Letters Patent.

Patented Nov. 17', 1908.

Application filed June 13, 1903, Serial No. 161,278. Renewed May 9, 1908. Serial No. 431,850.

To all whom it may concern:

Be it known that I, IiLLL-m. I-I. FREED- MAN, a citizen of the United States of America, and resident of Burlington, in the county of Chittenden and State of Vermont, have invented certain new and useful Improvements in Lag-Indicators, of which the following is a specification.

My invention relates to an instrument for measuring the lag or lead of the eurrent of an alternating or polyphase current circuit with respect to the pressure curve thereof, and my object is to produce an instrument which shall be simple in application and substantially accurate in its readings.

The. various scopes of the invention are attended to in the claims hereinafter annexed, but the general nature of the organization comprises two members mounted so as to be movable relatively to each other without mechanical restraint, means for developing a rotary field in one member, means for developing in the other member a rotary field having' the same direction of rotation as that of the first member, means for noting the relative movements of said members caused by the shifting of said fields, a brake acting on one member which is movable relative to the other to hold it stationary relatively to said other member, and means for regulating the force of said brake.

I have illustrated my improved instrument and the manner of using the same in the accompanying drawings, wherein Figure 1 is a longitudinal central section through a lag-indicator of my construction; Fig. 2 is a plan view thereof; Fig. 3 is a plan view of the same with the cover and pointer removed; Fig. 4 is a view similar to Fig. 1 of a modified form of instrument; Fig. 5 is a plan view of the same with the cover removed; Fig. G is a plan section of the same taken on the line 6 6 of Fig. 4; Fig. 7 is a view similar to Fig. 1 of a second modification; Fig. 8 is a plan view of the same with the cover removed; and Figs. 9 and 10 are diagranmiat-ic views, showing the electric connections of the instrument for a three and two-phase circuit respectively.

In the forni shown in Fig. 1, 12 is a base member comprising a circular block of insulating material on which are mounted posts 13, which support at4 their upper ends a ring 14, comprising an annular core of iron wire 15, having an enveloping winding of insulated copper 16, the whole being secured to the posts 13 by the straps 17. At the center of this ring 14 is mounted a second ring 18, which is similarly composed of an annular core of iron wire 19 and an exterior winding 20, this latter ring being supported on crosspieces 21 and secured thereto by straps 22. Through the center of the coil passes the supporting shaft 23, which is vert-ical and rests at its lower end in a hardened step block 24, which rests in a block 25 sliding in a socket 26 in the center of the base l2, and is adjust-able therein by means of a set screw 27, engaging with a piece 2S set in the base 12. The upper end of the shaft may be supported in a collar 29, which surrounds the same, and which forms one half of a ballbearing in conjunction with a stationary collar 30, between which run t-he balls 31. The collar 30 is secured to the cover plate 32 of a cylindrical casing 33, which is adapted to be secured to the base 12 by screws 34. The shaft 23 passes through a hole at the center of the casing as shown, and has at its upper end xed thereto a pointer 35 by means of a hand nut 3G screwing over the threaded stud 37 formed on the end of the shaft 23.

Around the side of the base block 12 are arranged two sets of terminals or binding posts 3S and 39 herein shown as six and three in number respectively, the machine illustrated being for three-phase circuits. The six binding-screws 38 are each connected to a wire-lead at equal angles around the stationary ring 14 on the coil 16, while the terminals 39 are likewise connected to the winding 2O of the ring 18. `In this latter case the leads 40 which connect the ring 13 to the terminals 39 are carried in toward the center, and preferably formed with'a quantity of loose vwire wound in spiral form as shown, whereby to allow the ring 13 to turn freely about its axis through an angle of about 9() degrees in either direction.

Vith the pointer 2O coperates a scale 41 on the upper side of the cover plate 32, this scale extending over 180 degrees of arc and being graduated on two sides. The graduations on the inner side of the scale 41 run at even agles from zero in the center up to 9() at either extremity, and the opposite sides are provided with the legends Lag and Lead respectively. The outer side of the scale 41 is graduated according to the cosine of the angle marked on the inner side, which varies from one at the center to Zero at either end, thus being proportional to the power factor, and the legend Power factor is marked on the outer side of the scale as shown.

The connections of the two rings 14 and 18 are such, with relation to the scale 41, that when two currents in phase with each other are sent through the respective coils, the pointer 35 will rest at the zero mark or center of the scale, but if one current lag behind the other', (suppose for instance the current in the inner coil lag behind that in the outer coil) then the poles of the rotating fields of the two coils will be no longer opposite each other, hence the inner coil will rotate until they come opposite each other, and the amount of this rotation will be strictly equal to the angle of lag if there is only one pair of poles in the rotating fields, but if there are two pairs of poles it will, of course, be equal to half the angle of lag, and so on. For obvious reasons lI prefer so to couple the two rings that they shall give but one pair of rotating poles each.

In order to hold the pointer 35 stationary until it is ready to be used, or to check its vibration at any time, I provide a brake in the form of a bell-crank lever 42, pivoted in ears 43 secured to one of the posts 13. This lever has a horizontally projecting arm with a fork 44 at its extremity, which embraces the shaft 23 and is adapted to co-act with a collar 45 fixed to the shaft immediately over the fork 44. The other arm of the bellcrank lever 42 extends downwardly, and against it presses the end of a set-screw 46 engaging in a socket in the post 13 and having a milled head 47 by which it may be turned. When the screw 46 is turned in, the fork 44 is raised and contacts with the collar 45, thus taking part of the weight off the shaft 23 from its bearings, and acting as a brake.

In Figs. 4, 5 and 6 is shown a modified form of instrument, having a base block 12, posts 13, a ring 14, and the brake mechanism as already described. The inner coil 18 as shown is also identical with that illustrated in Fig. 1, and is mounted on the cross-pieces 21, but in this case there is provided at the junction of the crosspieces 21 a cap-shaped pivot-block 48, which rests upon the upper end of a pivot-post 49 driven into the center of a pedestal-block 50, in the upper side of which are formed arcuate troughs 51 for mercury 52, which is placed therein. Into these troughs depend the wire leads 40 from the coil 20, so that the same isl enabled to rotate freely in either direction without any friction or other impediment which might tend to render the readings inaccurate. The mercury in the three vtroughs 51 is connected electrically with the respective terminals 39 as before, as shown at 53, Figs. 4 and 6. In this instance the brake fork 44 coacts with the pivot-cap 48 in raising it off the post 49 when it is desired to brake the apparatus. On the upper side of the coil 18 in this form of instrument rests a dial-plate 54, on which is marked a lag-and-lead and a power-factor scale 41, in the same manner as already exhibited in Fig. 2. With this coacts a stationary pointer 35, which is secured to one of the straps 17 of the stationary ring 14.V

It will be readily seen that this instrument acts substantially in the same manner as the first form described, except that the dial is stationary and the scale rotates. Hence connections should be in the opposite sense, or else the legends Lag and Lead should be interchanged upon the scale.

Another form of my improved lag-indicator is shown in Figs. 7 and 8, wherein the parts are identical with those described in Fig. 1, with the exception that the ring 18 is replaced by a straight bar 18, which is wound with a coil 20, this bar having only two terminal leads 40, which are connected respectively to the binding posts 39', there being two only of these in this case.

In connecting up the first two forms of the instrument described it is only necessary to connect one of the two coils in pressure relation, that is to say, across the poles of the circuit, and the other in series with the circuit, or in current relation, or in series-shunt therewith in the case of large circuits; and the rotating field produced by the latter coil will then obviously lag behind or lead that produced by the former by precisely the phase angle at which the current lags behind or leads the pressure curve of the circuit.

In the case of the instrument illustrated in Figs. 7 and 8 the connection is somewhat different, inasmuch as the inner coil is replaced by a bar having only two terminals, and which, therefore, produces only a pulsating magnetic field. I have illustrated this manner of connection in Fig. 9 for a threephase, and in Fig. 10 for a two-phase circuit. At 55 is a three-phase generator, the mains of which are designated 56, and which are connected through a triple switch 57 with Y.

the bus-bars 58. In the mains 56 is interposed the outer ring 14 of a lag-indicator of the type shown in Fig. 7, the mains 56 being represented as connected at three points in delta relation, in pressure relation with rec,

sistance in series from mains if necessary. The leads 40 of the bar 18 are then connected in series with one of the mains 56, as shown. Hence an alternating current will be sent through the coil 20 which will be in In Fig. 10, 55 represents a two-phase generator, the mains 56 of which are connected lOv through a four-pole switch 57 With the busbars 58, the connections in this case being simpler, as the coil let is connected in series With only tivo of the mains 56, these entering at angles of 90 degrees as shown, and leaving at points at 180 degrees dist-ant from the entering point. In this case the leads of the bar 1S are simply connected across between either pair 0f opposite mains 56 as shown.

The forms above illustrated for my improved lag andpovver factor indicator are only examples of the very numerous forms in Which my invention may obviously be embodied. Hence I do not desire to be restricted merely to the construction shovvn,but I desire to have it understood that my invention includes all mechanical and electrical equivalents for such constructions Which produce the same result and lie Within the scope of the following claims.

Having thus described my invention, what I claim as nevv and desire to secure by Letters Patent is l. .In combination, a polypliase circuit, a circular magnetic core, having a polyphase winding thereon connected in series with said circuit; an electromagnetic member mounted to rotate concentrically with respect to said core, and having a coil connected in pressure relation with said circuit, means carried by said rotatable member for indicating its angular position With respect to the other, a brake comprising a forked lever adapted to press endvvise against said movable meinbei, and a thumb-screw adapted to operate said brake. I

2. In combination, tivo members mounted so as to be movable relatively to each other Without mechanical restraint, means for developing a rotary field in one member, means for developing in the other member a rotary field having the same direction of rotation as that of the first member, means for noting the relative movements of said members caused by shifting of said fields, a brake acting on one member which is movable relative to the1 other, to hold it stationary relatively to said other member, and means for regulating the force of said brake.

3. A phase-indicator comprising tvvo members movable relatively toeach other Without restraint, means for setting up in said members rotary fields producing currents of the same frequency, said fields having the same direction of rotation, means for indicating the relative displacements of said members, a brake acting to check the movement of one member Which is movable relative to the other, and means for manually regulating the force of said brake.

In testimony whereof I have hereunto subscribed my hand and affixed my seal this ninth day of June 1903.

WILLIAM H. FREEDHAN.

Witnesses:

B. B. BALDWIN, P. I-I. VVHrrooMB.

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